Corrections needed when AliH2F was moved to CONTAINERS

[u/mrichter/AliRoot.git] / PYTHIA / jetset / luxkfl.F

 
C********************************************************************* 
 
      SUBROUTINE LUXKFL(KFL,ECM,ECMC,KFLC) 
 
C...Purpose: to select flavour for produced qqbar pair. 
      COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) 
      COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) 
      SAVE /LUDAT1/,/LUDAT2/ 
 
C...Calculate maximum weight in QED or QFD case. 
      IF(MSTJ(102).LE.1) THEN 
        RFMAX=4./9. 
      ELSE 
        POLL=1.-PARJ(131)*PARJ(132) 
        SFF=1./(16.*PARU(102)*(1.-PARU(102))) 
        SFW=ECMC**4/((ECMC**2-PARJ(123)**2)**2+(PARJ(123)*PARJ(124))**2) 
        SFI=SFW*(1.-(PARJ(123)/ECMC)**2) 
        VE=4.*PARU(102)-1. 
        HF1I=SFI*SFF*(VE*POLL+PARJ(132)-PARJ(131)) 
        HF1W=SFW*SFF**2*((VE**2+1.)*POLL+2.*VE*(PARJ(132)-PARJ(131))) 
        RFMAX=MAX(4./9.*POLL-4./3.*(1.-8.*PARU(102)/3.)*HF1I+ 
     &  ((1.-8.*PARU(102)/3.)**2+1.)*HF1W,1./9.*POLL+2./3.* 
     &  (-1.+4.*PARU(102)/3.)*HF1I+((-1.+4.*PARU(102)/3.)**2+1.)*HF1W) 
      ENDIF 
 
C...Choose flavour. Gives charge and velocity. 
      NTRY=0 
  100 NTRY=NTRY+1 
      IF(NTRY.GT.100) THEN 
        CALL LUERRM(14,'(LUXKFL:) caught in an infinite loop') 
        KFLC=0 
        RETURN 
      ENDIF 
      KFLC=KFL 
      IF(KFL.LE.0) KFLC=1+INT(MSTJ(104)*RLU(0)) 
      MSTJ(93)=1 
      PMQ=ULMASS(KFLC) 
      IF(ECM.LT.2.*PMQ+PARJ(127)) GOTO 100 
      QF=KCHG(KFLC,1)/3. 
      VQ=1. 
      IF(MOD(MSTJ(103),2).EQ.1) VQ=SQRT(MAX(0.,1.-(2.*PMQ/ECMC)**2)) 
 
C...Calculate weight in QED or QFD case. 
      IF(MSTJ(102).LE.1) THEN 
        RF=QF**2 
        RFV=0.5*VQ*(3.-VQ**2)*QF**2 
      ELSE 
        VF=SIGN(1.,QF)-4.*QF*PARU(102) 
        RF=QF**2*POLL-2.*QF*VF*HF1I+(VF**2+1.)*HF1W 
        RFV=0.5*VQ*(3.-VQ**2)*(QF**2*POLL-2.*QF*VF*HF1I+VF**2*HF1W)+ 
     &  VQ**3*HF1W 
        IF(RFV.GT.0.) PARJ(171)=MIN(1.,VQ**3*HF1W/RFV) 
      ENDIF 
 
C...Weighting or new event (radiative photon). Cross-section update. 
      IF(KFL.LE.0.AND.RF.LT.RLU(0)*RFMAX) GOTO 100 
      PARJ(158)=PARJ(158)+1. 
      IF(ECMC.LT.2.*PMQ+PARJ(127).OR.RFV.LT.RLU(0)*RF) KFLC=0 
      IF(MSTJ(107).LE.0.AND.KFLC.EQ.0) GOTO 100 
      IF(KFLC.NE.0) PARJ(159)=PARJ(159)+1. 
      PARJ(144)=PARJ(157)*PARJ(159)/PARJ(158) 
      PARJ(148)=PARJ(144)*86.8/ECM**2 
 
      RETURN 
      END